Interval training can cut exercise hours sharply

...Intense exercise regimens, or interval training, was originally developed for Olympic athletes and thought to be too strenuous for normal people.
But in recent years, studies in older people and those with health problems suggest many more people might be able to handle it. If true, that could revolutionize how officials advise people to exercise - and save millions of people hours in the gym every week. It is also a smarter way to exercise, experts say.

"High-intensity interval training is twice as effective as normal exercise," said Jan Helgerud, an exercise expert at the Norwegian University of Science and Technology...
This is sort of a "Duh!" for people who box or do boxing type cardio, but the key to this study is that it isn't just for the young and fit, but can work for older people and those who are not elite athletes.

Another part of the answers to, "Am I too old to box?" or "Do I have to be in top shape to train for boxing?"

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HerbM